7. The air that we breathe, chemically speaking, is a mixture of different gases, of which approximately 20 percent is oxygen and 79 percent nitrogen.

[译文]从化学上来说，我们所呼吸的空气是各种不同气体的混合物，其中约20%为氧，79%为氮。

[说明]句中主句的主谓语被定语从句that we breathe和插入语 chemically speaking 所分隔。

8. Our work in the prevention and treatment of diseases and medical research is advancing with big strides along the road of combining traditional and Western medicine.

[译文]我国的疾病防治和医学研究工作正在沿着中西医结合的道路向前迈进.

[说明]句中主谓语被起定语作用的介词短语in the prevention medical research 所分隔。

9. Thus it can be seen that immunity in its original meaning, referring to resistance to invasion by a parasite by means of specific immune response is only one activity of a cellular system in animals.

[译文]由此可见，免疫性一词的原意是指特异的免疫反应对入侵的寄生虫的抵抗,它仅是动物细胞系统的活动之一。

[说明]主语从句中的主谓语被介词短语in its…meaning和分词短语referring to…immune response所分隔。两者都起定语作用，修饰从句主语immunity.

10. Tepid baths, at skin temperature, when prolonged, appear to have a particularly soothing effect upon nerves.

[译文]接近皮肤温度的温水浴，如长期坚持，看来对神经具有特殊的镇静作用。

[说明]句中的主谓语被起定语怍用的介词短语at skin temperature 和省略成分的时间状语从句when prolonged所分隔。

11. The major complaints often associated with primary carcinoma of the liver which should alert the clinician to the diagnosis are pain in the right upper quadrant, unexplained fever, jaundice, a mass in the liver, rapid development of ascites and marked loss of weight.

[译文]原发性肝癍患者经常伴有一些重要的主诉，应引起临床医生作诊断时注意的是：右上腹疼痛、原因不明的发热、黄疸、肝内肿块、腹水迅速发展和体重明显减轻。

[说明]句中的主谓语被起定语作用的分词短语often associated …of the liver和定语从句which…to the diagnosis所分闷,两者都修 饰名词 complaints。

12. Severe sepsis and shock revealed by pallor, sweating, cold and clammy extremities, rapid pulse, hypotension, and stupor supervene when strangulation and perforation occur.

[译文]当绞窄和穿孔发生时，产生脸色苍白、出汗、四肢湿冷、脉搏加速、低血压和不省人事等症状所显示的严重脓毒症和休克。

[说明]主句的主谓语被起定语作用的分词短语revealed by ... and Stupor所分隔。